1. Field of the Invention
The present invention relates to a control device for a camera assemblage, to a camera assemblage for a vehicle, and to a method for controlling a camera of a vehicle.
2. Description of Related Art
In video systems of vehicles, the integration time or exposure time of a camera is adapted to the ambient light level. The video system or camera system is equipped for this purpose with a camera controller that, for example by evaluating a histogram or analyzing image data, determines the brightness of the ambient light and deduces from the determined measured values an integration time that ensures a good acquired image. Contrast, average value, moments, and percentiles can serve, for example, as measurement criteria.
In video systems in which a camera is fixedly associated with an application or function, image quality optimization can be directed by the camera controller specifically to the needs of that one application or function. Such applications or functions are, for example, lane detection, road sign detection, light assistant, or trajectory calculation or moving object detection (MOD), pedestrian detector, night vision.
As a result of the introduction of multipurpose camera (MPC) systems, the image signals are being used for multiple functions. As long as the functions or applications make the same or similar demands in terms of image quality, image quality optimization can be carried out directly. It becomes more difficult when different functions make mutually exclusive demands in terms of image quality.
Published German patent application document DE 698 08 024 T2 describes a method and an image acquisition apparatus for generating a video signal having an expanded dynamic range. Such systems are also known as high dynamic range (HDR) images, in which successive images are produced with different parameter settings, in particular with different exposure times, so that an optimized image can subsequently be created from image regions of differing brightness, for example by taking dark regions from the longer-exposure image and brighter regions from the shorter-exposure image. In this case the successive frames of the outputted image signal can be adjusted differently in direct fashion, so that a sequence of different frames is generated. For this, different exposure times are permanently set, and the images are then evaluated.
In Patent Abstracts of Japan JP 2002165138 A, a control device is described which accepts the continuous output of two images having different exposure times.